Vania



'L. BEHR Aug. 9, 1932.

METHOD OF AND APPARATUS FOR ELECTRICAL MEASUREMENT CONTROL Filed June-2, 1 2 2 Sheets-Shee l OOOOOOOO idgLZ/ENTOR I M5 6922+ A TTORA'E I Aug. 9, 1932. L. BEHR METHOD OF AND APPARATUS FOR ELECTRICAL MEASUREMENT CONTROL Filed June 2. 1927 2 Sheets-Sheet 2 in, ma MQAQ A TTORNEY ragengea gug. a, we:

, UNIIT'EDVSTATES PA'iiEnr: OFFICE i LEO BEER, or rnrnannnrnm, PENNSYLVANIA, assrcnon 'ro LEEDS & Non-razor comrm, vam

Application filed June 2,

' My invention relates to a method of and apparatus for determining one of a plurality of variables upon the product of which depends an electromotive force or diiference of potential.

' In accordance with my invention, there is provided a network for balancing against the aforesaid electromotive force or difference of potential, or an electromotive force directly proportional thereto, another electromotive force or difference of potential which bears a predetermined or known relation to an electromotive force representative of the variables other than the variable to be determined.

My invention-resides in a method of and apparatus for balancing a potential proportional to the roduct of two variable factors, more particu arly to such a product increased or decreased by a fixed amount, against a second potential proportional to one of said factors to determine the ratio between said 0- tentials, more particularly between the rst potential decreased or increased by said fixed amount and said second potential, expressed in terms of the other of said factors.

My invention resides also in methods, apparatus and circuit arrangement hereinafter described and claimed.

For an understanding of my method and for illustration of some of the forms my aparatus and circuits may take, reference is to e had to 'the accompanying drawings in which:

, Figs. 1 and 2 are explanatory diagrams.

Fig. 3 is a diagrammatic illustration of a network embodying my structure and suitable for' carrying out my method.

- Fig. 4 is in part a diagram and'in part a perspective of automatic, indicating, recording or control apparatus utilizing my invention.

' Fig. 5 is a diagram of circuit arrangements to produce an indication or measurement of ion concentration corrected or compensated for changes of a condition of the test cell electrodes, and to effect a control in response to said corrected measurement.

Without limitation of my invention thereto, and for a description of a system in which my invention is embodied, there is described 1927. Serial mfiesgi'e.

that specific applicatibnof my invention uti lizable for determining the ion concentration of electrolytes.

The relation between the concentration of a particular or selected ionand the potential difi'erence between electrodes/of predetermined nature in contact with the solution,

01 PHILADELPHIA, PENNSYLVANIA, A. CORPORATION OF PENNSYI4- containing the selected ion or ions, is known or determined. It has not been possible heretofore, however, to measure concentrations directly in terms of the potential difference as the latter is also affected by electrode changes, as per example, temperature changes.

description will be limited to a system which compensates for variations in' cell temperature affecting the. potential of a quinhydrone electrode used to measure the hydrogen. ion

concentration of potable water attemperapotential variation of any electrode, such astungsten, hydrogen gas, oxygen, air, or metallic electrode, due to temperature For the purpose of explanation only, the I changes whose electromotive force follows e voltage a=constant plus or minus 7:: con stant p ion concentration concentratio (more correctly log. t" te mperature of electrodes in C.

The potential of the 3 inhydrone elec-.

trode, against a saturate given by the expression:

, a specific example of the formula above.

calomel cell, is

the varialie portion of the expression for e, that is,

i t e 0.455 0.054054 Assuming that it is desirable to have acurrent of 0.001 ampere in the upper branch, its total resistance will equal 2024.8 ohms and the position of point C is therefore determined, for the illustration given, by the relationships,

B0" 89.64 O'A' 149.92

As C is never. actually used, as stated, to reach 0.455 volts above G to attain the point C", it is necessary to move 455 ohms to the left, which makes K=812 ohms. The purpose and values of resistances X and S C R are as follows The magnitude of resistance SCR is such that the product of this resistance and the current which is to be maintained constant therethrough is equal to the electromotive force of the standard cell SC, and in the present instance is 1,018 ohms. The value of X is such that the point C" has the appropriate potential with respect to point C, in the present instance being 194.8 ohms. 1

The point C" is connected to a fixed contact 'of a double pole, double throw switch, and when the movable contact blades of the latter are thrown'to the left, isplaced in connection with the quinhydro'ne electrode (Q E) of a test cell E through the galvanom'.

eter gl whose terminals are connected, respectively, to the movable contact blades of the switch.

The efiect of providing the point C" is that of having in a network, an impedance between C" and D only one of whose terminals D varies in potential with respect to any fixed reference po nt for different values of current passing through the impedance as distinguished from the impedance between points 0, D, both of whose terminals simultaneously varyfor a change of current there through.

The other electrode of the test cell E, which, as stated, may be a calomel half-cell C C is connected to the movable contact a of the slide wire SW of the potentiometer. To

determine the ion concentration of the solution in whichthe electrodes are placed, the

contact a is moved along the slide wire until the galvanometer gl shows no deflection.

The slide wire SW may be calibrated di- I rectly in concentration units or potential units, so that by mere inspection it is possible to read the ion concentration of a solution or a quantity indicative of said concentration" corrected for electrode changes. The double le switch is thrown to the right to connect the standard cell S O to the network only when the potentiometer current is to be checked. i

The network of Fig. 3 includes a circuit in the nature of a Wheatstone bridge, the latter comprising the impedance arms P, Q,, S and T, in one of whose conjugate conductors is included a source of electromotivev force or battery Gand in the other or second conjugate conductor is included an impedance which in the example illustrated comprises the resistance R and slide wire resistance with the magnitude of impedance, particuv larly T, in any bridge arm. The current through this second conjugate conductor is proportional to the difference of potential between the point 0, fixed or variable, in the conjugate conductor CD, and an imaginary point in the network external to the brid e, such for example as C, F igs. 2 and 3. T e potential of and at the point C is at a fixed diflerence from the potential at the point C.

A network of the character above described is generically of the character disclosed and claimed in my copending application Serial No. 92,158, filed March 4, 1926.

For 1 automatic indication, measurement, recording or control of ion concentration of a solution, any suitable apparatus may be employed. As an example, there may be utilized apparatus of the character disclosed the shaft or movable structure 10. In other words, the deflecting system of the galvanometer controls a disengageable connection between the electric motor M and the movable structure or shaft 10, whose direction and extent of movement depend upon theextent and sense of deflection of the mem-:, berN. The recording paper or sheet J is advanced at constant rate by the motor M 'past the marker or pen 7' which is moved transversely of the recordsheet by the movable structure 10. Upon the shaft 10 is secured the disk L upon which the slide wire SW of Fig. 3 is disposed.'

Fig. 4 corresponds with increase of H ion concentration and similarly traverse of the record paper'J by the marker 7' from left toward the right is in accord with increase of H ion concentration. For example, at the left margin of the paper may be a graduation corresponding to an H ion concentration of in Siirensons p value, while to the right may be graduations corresponding with magnitudes up to 8 at the right margin; the curve or record drawn by the marker 1} upon the'sheet J will, therefore, be a continuous I record of H ion concentration with respect to time.

- nometer 91, until eventually, when balance is As the movable structure is rotated in one direction or the other, theposition of the. contact 0 upon the .slide wire is varied in such sense as to tend to effect a balance of the character hereinb'efore described, cans ing reduction in the deflection of the galvaobtained, the galvanometer needle N is in its midposition and the movable structure 10 is not rotated in either direction until there oc-' curs a change in the ion concentration.

The apparatus may be utilized also for controlling or varying the magnitude of ion concentration, or for maintaining it constant. For this purpose, there may be secured upon the shaft 10 a cam disk 11 which, in rotation in one direction of shaft 10, closes the contacts 12, these contacts controlling, respectively, the direction of current through the armature of a reversible motor-13. Asimil'ar cam disk 11' actuates contacts 12 upon rotation of the shaft 10 in an opposite div the conduit 17 may control the delivery of lime to a mixing chamber 18. receiving wator. for drinking purpose from an inflow pipe 9, which after treatment passes through the out-flow pipe 20 to a point of consumption. This rate of delivery will be varied in proper sense and to properextent by the control i guitsuch as shcwxx n g- .mechanism of Fig. 1 under control of a db Clockwise rotation of the. slide wires in It will be appreciatedzthat in its broad aspect my invention is not limited to measurement of ionic concentration of a liquid, but may be utilized to determine any variable factor, the product of which and a second variable factor or'such product andan additive term is proportional to an electric potential. What I claim as my inventionv is: 1. The method of determining one of'twovariable factors whosepproduct is propor current which consists of producing change in current from another current source proportional to variations of the other of said factors, amplifying the effect of said current.

tional to a voltage derived from a source of. v

change to modify a second voltage derived from said second current source proportional to said current change, and balancing said -first voltage against said second voltage to determine their ratio in terms of said one of said factors. v 2. The method of determining one of two variable factors whose product is propor tional to a voltage derived from a source of current'which consists of producing change in current from another current source proportional to variations of the other of said factors, producing a second current change proportional to, but of a different order of magnitude than said first current change, to

modify proportionally a second voltage derived from said second current source, and balancing said first'v'oltage against said second voltage to determine their ratio in terms of said one of said factors.

3. Means for determining one of two vari-.

able factors whose product is proportional to a potential difference derived from a source of current, consisting of a second source of current an impedance having a difference of potential between two points thereof proportional to the other of said factors and derived from said second current source, and connections to permit a balance between said potential differences to be effected.

4. A composite network for determiningone of two variable factors whose product is proportional to a voltage derived from a source of current comprising a second source ofcurrent, component branches of said network traversed by current from said second source, one of said branches determining a oint of fixed potential, and other of said ranches determining a point whose potential differs from said fixed potential by an amount proportional to the other of said factors, and connections to permit the balancing of said potential difference derived front said second source of current against the voltage derived from said first sourceof current.

5. Means for determiningone of two variable factors whosefproduct is proportional to a voltage derived from a source of cursaid branches determining a point whose potential difiers from said fixed potential by an amount proportional to the other of said factors, and connections to permit the bal ancing of said potential difference against said voltage derived from said first source of current.

6. A network including a circuit in the nature of a Wheatstone bridge having a source of current in one of its conjugate conductors, of an impedance included in the second conjugate conductor of said bridge and traversed by the unbalance'current thereof, a conductor including a galvanometer connected between a variable point in said second conjugate conductor and a point in said network of fixed potential, and a second source of current in series with said galvanometer between said points.

7. A network including a circuit in the nature of a Wheatstone bridge having a source of. current in one of its conjugate conductors, of an impedance included in the second conjugate conductor of said bridge and traversed by the unbalance current thereof, a conductor including a galvanometer connected between a variable point in said second conjugate conductor of said bridge and a point in a branch of said network external to said bridge, and a second source of current in series with said galvanometer between said points.

8. A network including a circuit in the nature of a Wheatstone bridge having a source of current in one of its conjugate conductors, of an impedance included in the second conjugate conductor of said bridge, a conductor including-a galvanometer connected between a contact movable along said impedance and another point in said network, and a second source of current in series with said galvanometer between said contact and said point.

9. A network including a circuit in the nature of a Wheatstone bridge having a source of current in one of its conjugate conductors, of an impedance included in the second conjugate conductor of said bridge, a conductor v source of current in one of its conjugate conductors, of an impedance included in the a conductor including a galvanometer connected between a contact movable alon said impedance and a point in said nctwor external to said bridge, and a second source of current in series'with said galvanometer between said contact and said point.

11. A network includinga circuit in the nature of a Wheatstone bridge having a source of electromotive force in one of its conjugate conductors, of an impedance included in the second conjugate conductor of said bridge traversed by the unbalance current thereof, a conductor including a galvanometer connected between a point in said second conjugate conductor and another point in said network, an ion-concentration cellwhose terminal voltage is dependent upon the product of ion-concentration and temperature, in series in said conductor with said galvanometer, and an impedance in an arm of said bridge whose magnitude varies with temperature.

12. A network including a circuit in the nature of a Wheatstone bridge, of an impedance included in a conjugate conductor of said bridge, a conductor including a galvanometer connected between a contact variable along said impedance and another point in said network external of said bridge, an ionconcentration cell whose terminal voltage is dependent upon the product ion-concentration and temperature in series in said conductor with said galvanometer, an imped ance in an arm of said bridge whose magnitude varies with temperature, and a scale associated with said movable contact having mine their ratio.

LEO BEHR.

second conjugate. conductor nfenifl hr-icing 

